1. Field of the Invention
The present invention relates to a lower thread winding device which is used to wind a lower thread around a bobbin disposed within a bobbin case and, after then, deal with the lower thread extended from the bobbin case and guide it from an opening formed in the bobbin case to a slit formed in the bobbin case.
2. Description of the Related Art
Recently, for example, in Japanese Patent Publication No. 9-75570 of Heisei, there is proposed a lower thread winding device which is capable of executing an automatic winding operation to wind a lower thread around a bobbin.
The lower thread winding device of this type, for example, as shown in FIG. 2, comprises lower thread supply means 30 which is used to supply a lower thread L to a bobbin 15 disposed within a bobbin case 10, bobbin rotate means 20 which rotates the bobbin 15 in order to wind the lower thread L around the bobbin 15, and a thread handling member 40 which, in order to set one end side of the lower thread L under a lower thread tension adjust spring 11 disposed within the bobbin case 10 after the lower thread L is supplied to the bobbin 15, handles one end side of the lower thread L and guides it from an opening 10a to a slit 10b respectively formed in the bobbin case 10.
The lower thread supply means 30 comprises a thread supply nozzle 36 for guiding the lower thread from the leading end portion of the lower thread supply means 30, and a motor which is used to rotate the thread supply nozzle 36 in such a manner that the leading end portion of the thread supply nozzle 36 can be moved to an initial operation position N1 facing the opening 10a of the bobbin case 10, a lower thread winding position N2 spaced apart from the bobbin case 10, and a thread cutting position N5.
The bobbin rotate means 20 comprises a rotary body 25 disposed in such a manner that the bobbin 15 within the bobbin case 10 can be contacted with and removed from the rotary body 25, and buffer means 24 which is used to energize the rotary body 25 with a buffer force in a direction where the rotary body 25 is pressed against the bobbin 15; and, the bobbin rotate means 20 is structured such that it contacts and presses the bobbin 15 stored in the bobbin case 10 against the rotary body 25 to thereby rotate the bobbin 15.
The thread handling member 40 is formed in a shape which corresponds to the peripheral side surface of the bobbin case 10 and is structured such that it can be rotated around the bobbin case 10 along the bobbin case 10 peripheral side surface through a given course to handle the lower thread L extended to the opening 10a of the bobbin case 10, thereby moving the lower thread L from the opening 10a of the bobbin case 10 to the slit 10b thereof (see FIG. 5).
Referring here to the thread handling operation of related art to be executed by the thread handling member 40, as shown in FIG. 5, because it is necessary to pass the lower thread L between the edge portion 10g of the bobbin case 10 on the open surface 10f side thereof and the flange 15A of the bobbin 15, the thread handling operation is executed in such a state that the bobbin 15 stored within the bobbin case 10 is separated from the rotary body 25 of the bobbin rotate means 20 and the bobbin 15 is thereby free from the rotary body 25 However, in the above-mentioned conventional lower thread winding device, if the lower thread is wound around the bobbin nearly 100%, then the lower thread does not reach the slit of the bobbin case when carrying out the thread handling operation but stops halfway. As a result, in a thread guiding operation in which the lower thread is guided below the lower thread tension adjust spring of the bobbin case, because the lower thread has not arrived at the slit, the lower thread is guided in a poor manner.
Referring to the reason why the lower thread cannot reach the slit, if the lower thread is wound around the bobbin nearly 100%, then the portion of the lower thread that is extended out from the bobbin case lies down (that is, the guide portion of the lower thread extended externally of the bobbin lies on the bobbin peripheral edge side that is distant from the bobbin center portion, so that the guide angle of the lower thread extended externally of the bobbin becomes small) and, therefore, when the thread handling member moves on the edge portion of the bobbin case on the open surface side thereof to thereby guide the lower thread into between the present edge portion and the flange of the bobbin, the lower thread is unable to get into between them.
Also, in the above-mentioned lower thread winding device, in the thread handling operation, the bobbin is separated from the rotary body of the bobbin rotate means and is thus free. As a result, for example, when a firm thread is wound around the bobbin, there is a possibility that the flange of the bobbin can stick out from the bobbin case to thereby cause the lower thread to fly externally of the bobbin.
In order to prevent such fly-out of the lower thread, when a span thread or a cotton thread is used, the winding amount of the lower thread around the bobbin must be set less than or equal to 70-80% and, when a Tetoron thread is used, the winding amount of the lower thread around the bobbin must be set less than or equal to 50%.